1. Field of the Invention
The present invention relates to a disk drive, and particularly to head positioning control technology with disturbance compensation.
2. Description of the Related Art
Generally a head positioning control system for positioning a head at a target position (target track) on a disk medium is incorporated into a disk drive typically including a hard disk drive.
In the case of a disturbance having a large influence, such as a vibration and an impact, head positioning accuracy is decreased in the head positioning control system. Therefore, a disturbance compensation function of suppressing the disturbance which affects the head positioning accuracy is important in the head positioning control system of the disk drive.
With reference to the head positioning control system with the disturbance compensation function, there is proposed a system which uses a feedforward control system for suppressing the influence of disturbance by an adaptive filtering method (for example, see U.S. Pat. No. 5,663,847).
An acceleration sensor for observing (detecting) the disturbance is required in a head positioning control system in the prior art, in which the feedforward control system is used. Accordingly, when the head positioning control system of the prior art is applied to the disk drive, there are problems that the number of components is increased and the system structure becomes complicated in order to implement the system.